From: Jens Axboe Date: Tue, 20 Jun 2017 20:22:01 +0000 (-0600) Subject: null_blk: add support for shared tags X-Git-Url: http://git.cdn.openwrt.org/?a=commitdiff_plain;h=82f402fefa50;p=openwrt%2Fstaging%2Fblogic.git null_blk: add support for shared tags Some storage drivers need to share tag sets between devices. It's useful to be able to model that with null_blk, to find hangs or performance issues. Add a 'shared_tags' bool module parameter that. If that is set to true and nr_devices is bigger than 1, all devices allocated will share the same tag set. Signed-off-by: Jens Axboe --- diff --git a/drivers/block/null_blk.c b/drivers/block/null_blk.c index 586dfff5d53f..71f4422eba81 100644 --- a/drivers/block/null_blk.c +++ b/drivers/block/null_blk.c @@ -35,7 +35,8 @@ struct nullb { struct request_queue *q; struct gendisk *disk; struct nvm_dev *ndev; - struct blk_mq_tag_set tag_set; + struct blk_mq_tag_set *tag_set; + struct blk_mq_tag_set __tag_set; struct hrtimer timer; unsigned int queue_depth; spinlock_t lock; @@ -50,6 +51,7 @@ static struct mutex lock; static int null_major; static int nullb_indexes; static struct kmem_cache *ppa_cache; +static struct blk_mq_tag_set tag_set; enum { NULL_IRQ_NONE = 0, @@ -109,7 +111,7 @@ static int bs = 512; module_param(bs, int, S_IRUGO); MODULE_PARM_DESC(bs, "Block size (in bytes)"); -static int nr_devices = 2; +static int nr_devices = 1; module_param(nr_devices, int, S_IRUGO); MODULE_PARM_DESC(nr_devices, "Number of devices to register"); @@ -121,6 +123,10 @@ static bool blocking; module_param(blocking, bool, S_IRUGO); MODULE_PARM_DESC(blocking, "Register as a blocking blk-mq driver device"); +static bool shared_tags; +module_param(shared_tags, bool, S_IRUGO); +MODULE_PARM_DESC(shared_tags, "Share tag set between devices for blk-mq"); + static int irqmode = NULL_IRQ_SOFTIRQ; static int null_set_irqmode(const char *str, const struct kernel_param *kp) @@ -376,31 +382,8 @@ static blk_status_t null_queue_rq(struct blk_mq_hw_ctx *hctx, return BLK_STS_OK; } -static void null_init_queue(struct nullb *nullb, struct nullb_queue *nq) -{ - BUG_ON(!nullb); - BUG_ON(!nq); - - init_waitqueue_head(&nq->wait); - nq->queue_depth = nullb->queue_depth; -} - -static int null_init_hctx(struct blk_mq_hw_ctx *hctx, void *data, - unsigned int index) -{ - struct nullb *nullb = data; - struct nullb_queue *nq = &nullb->queues[index]; - - hctx->driver_data = nq; - null_init_queue(nullb, nq); - nullb->nr_queues++; - - return 0; -} - static const struct blk_mq_ops null_mq_ops = { .queue_rq = null_queue_rq, - .init_hctx = null_init_hctx, .complete = null_softirq_done_fn, }; @@ -592,8 +575,8 @@ static void null_del_dev(struct nullb *nullb) else del_gendisk(nullb->disk); blk_cleanup_queue(nullb->q); - if (queue_mode == NULL_Q_MQ) - blk_mq_free_tag_set(&nullb->tag_set); + if (queue_mode == NULL_Q_MQ && nullb->tag_set == &nullb->__tag_set) + blk_mq_free_tag_set(nullb->tag_set); if (!use_lightnvm) put_disk(nullb->disk); cleanup_queues(nullb); @@ -615,6 +598,32 @@ static const struct block_device_operations null_fops = { .release = null_release, }; +static void null_init_queue(struct nullb *nullb, struct nullb_queue *nq) +{ + BUG_ON(!nullb); + BUG_ON(!nq); + + init_waitqueue_head(&nq->wait); + nq->queue_depth = nullb->queue_depth; +} + +static void null_init_queues(struct nullb *nullb) +{ + struct request_queue *q = nullb->q; + struct blk_mq_hw_ctx *hctx; + struct nullb_queue *nq; + int i; + + queue_for_each_hw_ctx(q, hctx, i) { + if (!hctx->nr_ctx || !hctx->tags) + continue; + nq = &nullb->queues[i]; + hctx->driver_data = nq; + null_init_queue(nullb, nq); + nullb->nr_queues++; + } +} + static int setup_commands(struct nullb_queue *nq) { struct nullb_cmd *cmd; @@ -695,6 +704,22 @@ static int null_gendisk_register(struct nullb *nullb) return 0; } +static int null_init_tag_set(struct blk_mq_tag_set *set) +{ + set->ops = &null_mq_ops; + set->nr_hw_queues = submit_queues; + set->queue_depth = hw_queue_depth; + set->numa_node = home_node; + set->cmd_size = sizeof(struct nullb_cmd); + set->flags = BLK_MQ_F_SHOULD_MERGE; + set->driver_data = NULL; + + if (blocking) + set->flags |= BLK_MQ_F_BLOCKING; + + return blk_mq_alloc_tag_set(set); +} + static int null_add_dev(void) { struct nullb *nullb; @@ -716,26 +741,23 @@ static int null_add_dev(void) goto out_free_nullb; if (queue_mode == NULL_Q_MQ) { - nullb->tag_set.ops = &null_mq_ops; - nullb->tag_set.nr_hw_queues = submit_queues; - nullb->tag_set.queue_depth = hw_queue_depth; - nullb->tag_set.numa_node = home_node; - nullb->tag_set.cmd_size = sizeof(struct nullb_cmd); - nullb->tag_set.flags = BLK_MQ_F_SHOULD_MERGE; - nullb->tag_set.driver_data = nullb; - - if (blocking) - nullb->tag_set.flags |= BLK_MQ_F_BLOCKING; - - rv = blk_mq_alloc_tag_set(&nullb->tag_set); + if (shared_tags) { + nullb->tag_set = &tag_set; + rv = 0; + } else { + nullb->tag_set = &nullb->__tag_set; + rv = null_init_tag_set(nullb->tag_set); + } + if (rv) goto out_cleanup_queues; - nullb->q = blk_mq_init_queue(&nullb->tag_set); + nullb->q = blk_mq_init_queue(nullb->tag_set); if (IS_ERR(nullb->q)) { rv = -ENOMEM; goto out_cleanup_tags; } + null_init_queues(nullb); } else if (queue_mode == NULL_Q_BIO) { nullb->q = blk_alloc_queue_node(GFP_KERNEL, home_node); if (!nullb->q) { @@ -788,8 +810,8 @@ static int null_add_dev(void) out_cleanup_blk_queue: blk_cleanup_queue(nullb->q); out_cleanup_tags: - if (queue_mode == NULL_Q_MQ) - blk_mq_free_tag_set(&nullb->tag_set); + if (queue_mode == NULL_Q_MQ && nullb->tag_set == &nullb->__tag_set) + blk_mq_free_tag_set(nullb->tag_set); out_cleanup_queues: cleanup_queues(nullb); out_free_nullb: @@ -822,6 +844,9 @@ static int __init null_init(void) queue_mode = NULL_Q_MQ; } + if (queue_mode == NULL_Q_MQ && shared_tags) + null_init_tag_set(&tag_set); + if (queue_mode == NULL_Q_MQ && use_per_node_hctx) { if (submit_queues < nr_online_nodes) { pr_warn("null_blk: submit_queues param is set to %u.", @@ -882,6 +907,9 @@ static void __exit null_exit(void) } mutex_unlock(&lock); + if (queue_mode == NULL_Q_MQ && shared_tags) + blk_mq_free_tag_set(&tag_set); + kmem_cache_destroy(ppa_cache); }